1. Field of the Invention
This invention relates generally to communications receiver systems, and more particularly, to systems and methods for controlling affects of noise in signal receivers.
2. Description of Related Art
Electronic circuits that employ amplifiers in applications such as radio frequency (RF) receivers are designed to operate at a fixed noise figure (NF) in order to meet system specifications. Designers attempt through design and simulation efforts to determine where the noise figure operating point will be. However, a multitude of variables make it difficult to guarantee the operating point of the finished product. Such variables include, for example, silicon process variation, packaging assembly and simulation modeling. There may be many others depending on the application. Currently, few options are available for tuning the NF of a low noise amplifier (LNA) after the product has been processed and assembled. In most cases, particularly in the case of other receiver circuits, the NF is fixed and receiver system performance must be accepted.
In addition, LNA's are not the only components in a circuit for which a NF is specified. Other components in any given circuit may also operate at a NF. The circuit or system may therefore operate at a system noise figure, which is a cumulative function of the NF of each circuit element in the receiver chain. Thus, the deleterious effect of the many variables on system performance may be compounded by the cumulative effect on multiple circuit elements in a circuit.
One of the biggest tradeoffs in meeting noise-figure requirements is power consumption. There are numerous methods for reducing power consumption in receivers. Typical implementations shutdown or cutback the current in the receiver circuits, depending on whether the receiver is in normal operating mode or in standby mode. Receivers typically operate in one operating mode at a fixed current and power consumption. In environments with higher signal strength or reduced noise it is possible to maintain receiver performance or functionality at a lower operating current.
It would be desirable to employ a method or system that will dynamically and automatically reduce the current consumption. It would also be desirable to employ a method or system to tune the noise figure of one or more components in an application to adjust the total system noise figure.